a. The Field of the Invention
This invention relates to marine propulsion apparatus of the type comprising a rearwardly directed jet orifice connected to pumping means which is adapted to take water from outside a boat or the like vessel with which said marine propulsion apparatus is associated and to discharge a jet of water into the air astern of the vessel from said jet orifice in a manner such as to drive the boat or the like vessel.
B. The prior Art
At present these marine propulsion apparatus are associated with means comprising some form of deflecting device including a direction of travel control member so shaped and mountable that it can be interposed in the path of the jet of water for deflecting such jet forward and thus causing the boat to go astern, and the control member can be removed completely from the path of the discharged jet of water to allow said jet to propel said boat forwardly. Further, some laterally deflecting device, generally one or more swingable rudder blades or a laterally swingable tube means, is provided for selectively deflecting said jet of water leftwardly or rightwardly of the longitudinal plane of symmetry of the boat for directionally controlling and altering the course of the boat. Still further, the pumping means are actuated by some suitable source of power, generally an internal combustion engine provided with conventionally operated throttle means, whereby the power applied to said pumping means and consequently the speed of ejection and the rate of flow of the jet can be adjusted. Therefore, by operating suitable control means, the boat or like vessel to which a marine propulsion apparatus of the kind referred to above is associated, can be governed at will, either as to its speed, course and/or direction.
It is however well known to those skilled in the art that any marine propulsion apparatus of the kind referred to above, more generally and simply termed "water jet units", while very satisfyingly operating for regular forwardly directed thrust, that is when the water jet is neither intercepted nor deviated (the advantages of such water jet units for marine propulsion, particularly for relatively small boats, are so widely known that further comments are unnecessary), provide an undesirably poor control and efficiency when the boat is performing sharp radius turns and a still less efficient and poorer response during low speed maneuvers, principally when the boat is in reverse. The improved apparatus described and shown in my prior U.S. application Pat. No. 3,465,705 and in the British Patent Specification No. 1,204,794 has provided a more satisfying control in low speed maneuvers but the efficiency of propulsion when maneuvering in reverse is not as high as is desired.
The fact that principally leads to the above and other objectionable characteristics in the efficiency of the known water jet propulsion units for boats consists of the excessive turbulence and the partial and irregular re-direction of the water which is flowing from the jet opening at considerable velocity.
It is therefore an object of this invention to provide water flow control means for controlling the motion of a boat having a marine propulsion apparatus of the water jet type, which will obviate or at least drastically minimize the foregoing and other difficulties and limitations.